OBJECTIVE: The overall goal of this project is to improve the understanding of the role of dietarycarotenoid intake in the etiology and prevention of cancer by applying the USDA-NCI carotenoid database to epidemiologic studies. BACKGROUND: Epidemiologic studies consistently show reduced risk for cancer associated with increased intake of fruits and vegetables, rich sources of carotenoids. To improve dietary assessment of carotenoids in epidemiologic studies, the USDA- NCI carotenoid database was developed and contains values for five carotenoids: alpha-carotene, beta-carotene, cryptoxanthin, lutein/zeaxanthin, and lycopene. Total carotenoid intake can be calculated by summing all five. METHODS: The National Health Interview Surveys have been used to compare dietary carotenoid intake among U.S. adults by demographic and lifestyle characteristics in order to identify high risk groups for chronic disease prevention efforts. In addition, the Nurses Health Study has been used to estimate the diet-plasma carotenoid relationship and to estimate the relative risks of breast cancer incidence by level of carotenoid intake alone and in relation to recognized risk factors for breast cancer. PROGRESS: The National Health Interview Surveys: In 1987, carotenoid intake was lower among current smokers vs. non-smokers, the less educated vs. college educated, younger adults (aged 18-39 yr) vs. older adults, those who regularly eat meals at restaurants vs. those who eat at home, and women who take oral contraceptives vs. non-users. Between 1987 and 1992, lutein intake declined among white females, non-drinkers and drinkers of 1-6 drinks/week, and residents of the South and Northeast. Lutein is found in foods rich in folate and other antioxidants, and therefore the overall decline in lutein may have public health implications associated with increased risk of chronic disease. The Nurses Health Study: Among non-smoking women, the adjusted diet- plasma carotenoid associations were 0.48 for alpha-carotene, 0.27 for beta-carotene and lutein, 0.32 for beta-cyptoxanthin, and 0.21 for lycopene. Correlations between total fruit or vegetable intake and each plasma carotenoid level were not as high as any of the calculated carotenoid intake using the USDA/NCI carotenoid data base. Intakes of lutein/zeaxanthin, beta-carotene with supplements, carotenoid vitamin A and total vitamin A were inversely associated with the risk of premenopausal breast cancer. These inverse associations were strongest among premenopausal women with a positive family history of breast cancer in a first-degree relative, women at elevated risk due to consuming 15 /d of alcohol. Intakes of these nutrients were inversely associated with risk of postmenopausal breast cancer among women who were currently using hormone replacement therapy. -cancer, Epidemiology, diet, carotenoids, -Human Subjects